1. Technical Field
The present invention relates to a printer having an inverting path that reverses the front and back sides of recording paper or other sheet media and then feeds the inverted media back into the printing path.
This application is based upon Japan Patent Appl. Pub. No. 2014-040163 filed on Mar. 3, 2014, and Japan Patent Appl. Pub. No. 2014-168235 filed on Aug. 21, 2014, the entire contents of which are incorporated by reference herein.
2. Related Art
Examples of printers with an inverting path are printers with an automatic duplex print function such as described in Japan Patent 3847149 and JP-A-2013-241278. These printers have a supply path that conveys recording paper to be printed on from a supply unit, a main conveyance path passing where the recording paper is printed on, and an inverting path that reverses the front and back sides of the paper after printing on the first side. A diverter for switching the conveyance path is disposed between the upstream end of the main conveyance path and the upstream end of the inverting path. The supply path and the inverting path merge at the downstream ends thereof and then connect to where the diverter is disposed. The recording paper is guided from the supply path or the inverting path to the main conveyance path by the diverter, and the recording paper is guided to the inverting path after the first side is printed on the main conveyance path.
In the printer described in JP-A-2013-241278, a second supply roller is disposed as a conveyance roller in the supply path. The recording paper supplied from the supply unit is conveyed by the second supply roller toward the main conveyance path, and is then passed to the main conveyance roller disposed to the main conveyance path. Even recording paper that is short in the conveyance direction can be conveyed by the second supply roller.
In the printers with an inverting path as described in Japan Patent 3847149 and JP-A-2013-241278, a path switching unit comprising the diverter and the merging portion with the downstream end of the inverting path is disposed to the conveyance path between the supply unit and the print position on the main conveyance path. The length of the conveyance path from the supply unit to the print position therefore increases. A conveyance roller such as described in JP-A-2013-241278 may also be required to print on short recording paper. Making a printer with an inverting path such as described above small and compact is therefore difficult because the conveyance path is long and a conveyance roller for conveying short recording paper is required.
Because the supply path and the inverting path merge together, there can be a difference in elevation or a discontinuity between the conveyance guide surfaces of the conveyance paths where they merge. The recording paper can therefore easily jam where the conveyance paths merge. More specifically, because the leading end part of the recording paper can easily curl after printing on the first side, the recording paper may jam where the conveyance paths merge after printing the first side. Problems such as deviation in the conveyance precision of the recording paper where the paths merge can also result from the difference in elevation or discontinuity between the conveyance guide surfaces.